The present invention relates to the automatic production of filter bags, preferably of filter paper, containing products such as tea, chamomile and similar herbs designed to be immersed in a liquid in order to make infusions for various uses, for example, as beverages or for diverse medicinal purposes.
More specifically, the invention relates to an apparatus used in a continuous production process for automatically forming envelopes in which the filter bags containing the infusion product are accommodated, and which may if necessary, be sealed, for purposes of hygiene and in order to maintain the flavor and other characteristic properties of the infusion and/or to protect the filter bags themselves.
In the automatic production of filter bags for infusion products, the preparation of the envelopes and the insertion of the filter bags into them are performed, as is known, by special devices or units which: process webs of envelope paper; fold them onto themselves; associate them with filter bags received from a filter bag making machine; and seal the paper webs to form a continuous succession of chambers, each containing a filter bag, which are then separated from each other and sent to a further packaging unit.
In the process outlined above, the filter bags and the envelope paper web are fed along separate feed paths and the bags are associated with the web by intermittent, synchronized reciprocating movements at an area where their two paths intersect.
This type of process cycle requires filter bag making machines and devices or machine stations which wrap the filter bags in the envelopes which are extremely complex and whose maximum production speed is limited also by the type of feed paths followed by the bags and paper web and by the intermittent, reciprocating motion of the components.
The aim of the present invention is to overcome the above mentioned disadvantages by providing an apparatus in which the envelopes are formed and the filter bags associated with them according to continuous relative feed movements along feed paths which, in particular at the area where the filter bags are associated with the envelopes, are substantially parallel and run in the same direction.